Problem: Solve for $y$ : $6 = y + 30$
Subtract $30$ from both sides: $ \begin{eqnarray} \\ \hphantom{6 {- 30}} &\hphantom{=}& \hphantom{y} \\ 6 &=& y + 30 \\ \\ {-30} && {-30} \\ \end{eqnarray} $ $ \begin{eqnarray} \\ 6 {- 30} &=& y \\ \end{eqnarray} $ Simplify. $ y = -24$